JP6173443B2 - Method for manufacturing thermoelectric components and thermoelectric components - Google Patents

Description

  The present invention relates to a method for manufacturing a thermoelectric component and the thermoelectric component itself.

  Thermoelectric modules are used individually or in large numbers as thermoelectric generators that generate electrical energy from temperature potentials and the resulting heat flow. Electric energy is generated based on the so-called Seebeck effect. The thermoelectric module is composed of p-doped and n-doped thermoelectric components that are electrically connected to each other. The thermoelectric component comprises a so-called hot side and a cold side arranged oppositely, through which the thermoelectric components are each connected in electrical conduction alternately to further thermoelectric components arranged next to each other. The hot side is thermally conductively connected to the wall of the thermoelectric module, in which it is subjected to the action of a hot medium (eg exhaust gas). Correspondingly, the cold side of the thermoelectric component is thermally conductively connected to another wall of the thermoelectric module that is subjected to the action of a cold medium (eg, cooling water).

  Thermoelectric generators are used in particular in automobiles, but are also used in other technical areas where the temperature potential can be utilized for the production of electrical energy by the arrangement of thermoelectric generators.

  The thermoelectric component is exposed to a temperature potential during operation of the thermoelectric generator, so that a heat flow flows between the hot side and the cold side of the thermoelectric component to generate electrical energy. Furthermore, thermoelectric components are subject to fluctuating thermal stresses, which result from temperature values that vary on the hot side and on the cold side. This load may cause failure of the thermoelectric component, and at least the effectiveness of the conversion of thermal energy into electrical energy is reduced.

  The object of the present invention is therefore to at least partly solve the problems presented in connection with the prior art. In particular, a method for the manufacture of a thermoelectric component should be indicated, which can provide a thermoelectric component that is durable and robust against fluctuating thermal stresses. Furthermore, a corresponding thermoelectric component should be proposed, and the thermoelectric component is made so that it can withstand a corresponding load permanently.

  These problems are solved by a method for manufacturing a thermoelectric component according to the features of claim 1 and by a thermoelectric component according to the features of claim 5. Further advantageous configurations of the invention are indicated in the dependent claims. It is pointed out that the features individually recited in the claims can be combined with each other in any technically significant way and represent further embodiments of the invention. The specification describes the invention in more detail and gives additional examples of the invention, particularly in connection with the figures. It is further pointed out that the use of the thermoelectric components proposed here is not limited to automobiles. The following detailed description of the method according to the invention applies correspondingly to the thermoelectric component according to the invention to the extent technically significant.

The method for the production of thermoelectric components according to the invention comprises at least the following steps:
a) providing at least one fiber;
b) coating at least one fiber with a thermoelectric material so that at least one coated fiber is formed;
c) at least one coated fiber is at least rolled into a ring having a central axis, and more particularly,
d) Pressing the ring to produce the thermoelectric component.

  The method is preferably carried out one after the other in the order a) to c), in particular in the order a) to d), in particular the steps a), b) and c) can be repeated several times and / or with each other. It may be performed in parallel. In particular, the method comprises further steps in between, for example for the treatment of fibers, coated fibers and / or rings.

  The fibers in particular have at least one of the following properties: long, extending, filamentous, elastic, preferably round cross-section, preferably a length 100 times greater than the fiber diameter, minimum diameter 0.5 micrometers, diameter up to 5 micrometers. In particular, the method includes that exactly one, preferably but many, fibers for the manufacture of thermoelectric components are used.

  Desirably, the at least one fiber consists of a non-thermoelectric material, in particular a ceramic material. In particular, the following materials are proposed, and the following materials can be used individually or in combination with one another: aluminum oxide, zirconium oxide.

In particular, a thermoelectric material is used in step b), the thermoelectric material having at least one of the following materials:

  According to one particularly advantageous configuration, the at least one fiber is designed in harmony with the thermoelectric material with respect to at least one material property. In particular, at a temperature range of at least 150 ° C. to 600 ° C., the coefficients of thermal expansion of the fiber and of the thermoelectric material are consistent with each other and desirably differ from each other by a maximum of 10%, in particular only a maximum of 2%.

Desirably, the at least one fiber exhibits the following material properties:
The fiber material has a higher strength than the thermoelectric material;
• Tensile strength of the fiber material greater than 100 N / mm ² [Newtons per square millimeter] • Compressive strength of the fiber material greater than 500 N / mm ²

  The coating of the at least one fiber with the thermoelectric material is preferably performed by vapor deposition of the thermoelectric material onto the fiber, for example by CVD (chemical vapor deposition) or PVD (physical vapor deposition) methods. However, other methods can be used for the coating step.

  Desirably, the at least one coated fiber is wound into a ring having a central axis such that at least one coated fiber is wound about the central axis. In particular, at least one fiber is additionally folded. In particular, the ring has an inner diameter and an outer diameter. In particular, the method produces a (cylindrical) disc element, which therefore has no inner diameter (ie a ring with an inner diameter of 0 mm).

  The optional proposed compression of the ring or of the at least one coated fiber is in particular carried out at a temperature [degree of Celsius] of at least 250 ° C., preferably for pressure production of at least 2 bar. Applies. Desirably, the temperature is greater than 500 ° C. and a pressure of at least 2.5 bar.

  For the production of thermoelectric components, in addition to the thermoelectric material for the coating of the fibers, further thermoelectric materials can certainly be added, in particular at or after step c), the thermoelectric component being ( Rather than consisting only of (compressed) coated fibers, the thermoelectric material additionally forms a ring. Desirably, the thermoelectric component is, however, exclusively formed by at least one coated fiber.

  According to one particularly advantageous configuration, the thermoelectric component created after step d) has a first extension along the axial direction, and in step d1), several by a splitting process (eg cutting) (At least two) each of which is divided axially into rings having a smaller second extent.

  In particular, the first spread is at least 2 mm, desirably at least 10 mm. The second spread is correspondingly at least 1.0 mm.

  In particular, step c1) can be followed by step c1), in which the ring created in step c) is divided into several (at least two) rings by a splitting process. . Correspondingly, the thermoelectric component created after step d) is then not further divided. In particular, in the case of disc elements manufactured by this method, the inner diameter is introduced in a further step. This step is preferably carried out following step c), c1) or d).

  In particular, the at least one coated fiber spans an angular range of at least 120 ° [degree (angle)], preferably at least 360 °, particularly preferably at least 420 °, in the circumferential direction of the manufactured thermoelectric component. Extend. In particular, the at least two coated fibers overlap in the circumferential direction over an angular range of at least 5 °. Thereby, it is ensured that the thermoelectric material has the advantageous material properties provided by the fibers.

  According to the invention, a thermoelectric component comprising at least one fiber coated with a thermoelectric material is further proposed, wherein the thermoelectric component is formed in an annular shape, and the at least one coated fiber is at least 120 ° in the circumferential direction. Extending over an angular range of preferably at least 360 °, particularly preferably of at least 420 °. In particular, the thermoelectric component is manufactured according to the method according to the invention.

Desirably, the non-thermoelectric material accounts for 20 to 80% by weight of the thermoelectric component, particularly 35 to 65% by weight. According to one advantageous configuration of the thermoelectric component, the non-thermoelectric material has at least one characteristic from the following group in the temperature range of 20 ° C. to 600 ° C .:
- tensile greater than thermoelectric material strength _{R m} and / or yield point _{R p0.2,}
-Specific heat conductivity [watt / (Kelvin meter)] less than thermoelectric material,
-Less electrical conductivity [ampere / (volt-meter)] than thermoelectric materials.
Desirably, there are also some or all of these characteristics.

  Properties assist the desired function of the thermoelectric component, such as, for example, improved tensile strength, (in some cases, locally predetermined or adapted) thermal conductivity and / or adapted electrical conductivity. However, the last property can be used especially for improving the efficiency of thermoelectric components.

  In particular, it is envisaged that the non-thermoelectric material is arranged here in the thermoelectric component as a thermal insulator.

  In particular, it is envisaged that non-thermoelectric materials are not used as electrical conductors, ie here they do not fulfill the function of the thermoelectric material (Seebeck / Peltier effect). In particular, the thermoelectric effect is caused in thermoelectric components only by thermoelectric materials.

  In particular, due to the use of non-thermoelectric materials in the thermoelectric component, the thermal conductivity of the thermoelectric module composed of the corresponding thermoelectric component is at one operating point across the thermoelectric module, ie between the hot side and the cold side. It is possible to adjust the total temperature difference (between exhaust gas and refrigerant) to be reduced to 20% to 80%, in particular 35% to 65%. In this connection, reference is made to German Offenlegungsschrift 102010030259A1, the entire contents of which are referred to here for the description of the technical circumstances. Reference to “foreign matter” in that document relates here to “non-thermoelectric material”.

  The method and thermoelectric component proposed here are characterized by a special arrangement of fibers coated with thermoelectric material. This fiber, especially made of ceramic material, clearly increases the mechanical strength and durability against fluctuating heat loads, so that a durable thermoelectric module can be provided. In particular, at least one fiber absorbs forces in the circumferential direction of the ring. Desirably, the creep of the thermoelectric material is thus reduced or even completely prevented.

  Furthermore, an automobile is proposed, the automobile comprising at least an internal combustion engine, an exhaust gas system and a thermoelectric module, the thermoelectric module being manufactured according to at least one thermoelectric component according to the invention or a method according to the invention. At least one thermoelectric component. Thermoelectric modules are designed to generate electrical energy from the exhaust gas thermal energy.

  The invention and the technical periphery will be described in more detail below on the basis of the figures. Although the figure shows a particularly preferred embodiment, the invention is not so limited. In the figures, the same reference numerals are used for the same objects. This is shown schematically in the figure.

Fig. 2 shows a fiber according to step a) of the method. Figure 3 shows a coated fiber according to step b) of the method. FIG. 3 shows in plan view a rolled, coated fiber 4 according to step c) of the method. The wound, coated fiber 4 according to step c) of the method is shown in side view. Fig. 2 shows a thermoelectric component according to step d) of the method. Fig. 2 shows a thermoelectric component according to step d1) of the method. Indicates a car.

  FIG. 1 shows the provision of a fiber 2 according to step a) of the method for the production of a thermoelectric component 1.

  FIG. 2 shows a coated fiber 4 produced by step b) of the method, which was coated with a thermoelectric material 3.

  FIG. 3 shows a wound coated fiber 4 according to step c) of the method. Here, the wound, coated fiber 4 is shown in plan view. The coated fiber 4 is wound into a ring 5, and the coated fiber 4 extends in the circumferential direction 9 over an angular range 10.

  FIG. 4 shows in side view a wound, coated fiber 4 according to step c) of the method. The coated fiber 4 was wound around a central axis 6 to form a ring 5.

  FIG. 5 shows the thermoelectric component 1 produced according to step d) of the method. The ring 5 having the central axis 6 is compressed by the device 18 into the thermoelectric component 1 by at least one pressing force 17. In the shown cross section of the thermoelectric component 1, the fibers 2 of the coated fibers 4 can be seen.

  FIG. 6 shows the thermoelectric component 1 after step d1) of the method. In that regard, the thermoelectric component 1 provided in the form of a ring 5 and extending over the first extension 7 along the axial direction 8 is divided into two thermoelectric components 1 by a split 19. Such thermoelectric components 1 each have a smaller second extension 16 after the division 19. The thermoelectric component has an inner diameter 22 and an outer diameter 23.

  FIG. 7 shows an automobile 12 having an internal combustion engine 13 and an exhaust gas system 14, and a thermoelectric module 11 is arranged in the exhaust gas system 14. The exhaust gas 15 flows from the internal combustion engine 13 through the exhaust gas system 14 and the thermoelectric module 11 to the surroundings. The cooling device 20 is connected to the internal combustion engine 13 and to the thermoelectric module 11 for cooling. The low temperature medium 21 flows from the cooling device 20 toward the thermoelectric module 11. The thermoelectric module 11 is configured in a tubular shape and includes an annular thermoelectric component 1, and the annular thermoelectric component 1 is continuously disposed along the axial direction. The thermoelectric module 11 includes a cold side on the inner pipe line, and the cold medium 21 flows through the cold side. The hot side is here arranged on the outer surface. On the outer surface, the thermoelectric module 11 hits the exhaust gas 15. A temperature potential is correspondingly established between the exhaust gas 15 and the low temperature medium 21 over the thermoelectric module 11, and a current is generated by the thermoelectric component 1.

DESCRIPTION OF SYMBOLS 1 Thermoelectric component 2 Fiber 3 Thermoelectric material 4 Coated fiber 5 Ring 6 Central axis 7 First spread 8 Axial direction 9 Ambient direction 10 Angular range 11 Thermoelectric module 12 Automobile 13 Internal combustion engine 14 Exhaust gas system 15 Exhaust gas 16 Second spread 17 Pressing force 18 Device 19 Division 20 Cooling device 21 Low temperature medium 22 Inner diameter 23 Outer diameter

Claims (6)

A method for manufacturing a thermoelectric component (1) comprising at least the following steps:
a) providing at least one fiber (2);
b) coating at least one fiber (2) with a thermoelectric material (3) so that at least one coated fiber (4) is formed;
c) at least one coated fiber (4) is at least rolled into a ring (5) having a central axis (6) , wherein the at least one coated fiber (4) has an angular range of at least 360 ° ( 10) over the central axis (6) over a step,
d) pressing the ring (5) with a pressure of at least 2 bar to create the thermoelectric component (1);
Including methods. 2. The method according to claim 1, wherein the thermoelectric component (1) produced in step d) has a first extension (7) along the axial direction (8) and is performed after step d). In step d1), the axial process (8) is divided into a plurality of thermoelectric components (1) each having a smaller second extent (16) by a splitting process. Method according to claim 1 or 2, wherein the at least one coated fiber (4) extends in the circumferential direction (9) of the thermoelectric component (1) over an angular range (10) of at least 360 °. Method.   4. The method according to one of claims 1 to 3, wherein at least one fiber (2) consists of a ceramic material. A thermoelectric component (1) comprising at least one fiber (4) coated with a thermoelectric material (3), the thermoelectric component (1) being annularly formed and having at least one coated fiber (4 ) is circumferentially (9), extending beauty over at least 360 ° angular range (10),
Thermoelectric components whose fibers (4) and thermoelectric material (3) have a coefficient of thermal expansion that differs from each other by a maximum of 10% in a temperature range of 150C to 600C .   An automobile (12) comprising at least an internal combustion engine (13), an exhaust gas system (14), and a thermoelectric module (11), wherein the thermoelectric module (11) is at least 1 according to claim 5. An automobile comprising two thermoelectric components (1) and made to generate electrical energy from the thermal energy of the exhaust gas (15).

Images